If you encounter issues in Lightroom Classic when trying to merge a converted catalog into a larger master catalog, then try the following:
- open the converted project ONCE in Lightroom Classic,
- choose File > Optimize Catalog... to let Lightroom do the correct housekeeping in the database,
- then switch to your master catalog.
- launch Lightroom CC
- choose File > Import from Another Catalog...
If you still encounter errors, please contact us